Dr. Charles DeCarli, a neurologist at the University of California, Davis Medical School, is studying the many ways that vascular disease injures the brain. "Twenty years ago, when researchers talked about diseases that affect the blood vessels of the brain, they were referring to strokes." With MRIs and other sensitive brain imaging tools, researchers can now visualize earlier stages of vascular disease in the brain. "We've moved from stroke to so-called silent strokes (strokes without symptoms), to small strokes called lacunae, to a type of very early injury called white matter hyperintensities. This has changed how we think about the ways vascular disease injures the brain."
When large blood vessels in the brain are completely blocked, a stroke occurs, significantly damaging an area of the brain. But earlier, less dramatic blockages can also damage the brain. Dr. DeCarli calls strokes "the tip of the iceberg of cerebrovascular disease." Some smaller vessels of the brain can become blocked, causing damage that produces no immediately discernable symptoms. These silent strokes may occur in as many as one in four people over the age of seventy-five. Other researchers have found that silent strokes double the risk of dementia, and that this kind of cerebrovascular disease intensifies the severity of AD.
Dr. DeCarli is also studying how vascular disease can harm neurons by damaging the axons. As we've seen, neurons communicate with each other by sending signals down the axon of one neuron and across the synapse to be received by the dendrite of a neighboring neuron. In order to better carry an electrical charge, the axon is insulated along its length by myelin, a fatty sheath produced by one of the brain's supporting cell types. By depriving it of blood and nutrients, vascular disease can damage the myelin. When this happens, the electrical impulse cannot travel as efficiently along the axon, and the neuron may not be able to send its signal to the neighboring cell. When neurons stop communicating, cognitive and other problems occur.
Dr. DeCarli and his team have refined MRI techniques to create a visual image of injured myelin around the axons. Damage shows up as bright white areas on a scan—what are called hyperintensities. "We're beginning to see evidence that if the axon is hurt by vascular disease, the whole nerve cell may die."
Excerpted from THE ALZHEIMER'S PROJECT: MOMENTUM IN SCIENCE, published by Public Affairs, www.publicaffairsbooks.com.
In This Section
- Vascular Disease
- Insulin Resistance and Diabetes
- Connecting Alzheimer's Disease to Vascular Disease
- Vascular Injury
- Vascular Dementia and Alzheimer's Disease
- The Problem of Cholesterol
- What's Good for the Heart is Good for the Brain
- Atherosclerosis and Alzheimer's Disease
- Associating Alzheimer's Disease with Insulin Resistance and Diabetes
- Diabetes and Insulin Resistance
- Insulin in the Brain
Momentum in Science: The Supplementary Series
- Understanding and Attacking Alzheimer's 12 min
- How Far We Have Come in Alzheimer's Research 15 min
- Identifying Mild Cognitive Impairment 20 min
- The Role of Genetics in Alzheimer's 12 min
- Advances in Brain Imaging 11 min
- Looking Into the Future of Alzheimer's 6 min
- The Connection Between Insulin and Alzheimer's 21 min
- Inflammation, the Immune System, and Alzheimer's 29 min
- The Benefit of Diet and Exercise in Alzheimer's 16 min
- Cognitive Reserve: What the Religious Orders Study is Revealing about Alzheimer's 20 min
- Searching for an Alzheimer's Cure: The Story of Flurizan 30 min
- The Pulse of Drug Development 15 min
- The DeMoe Family: Early-Onset Alzheimer's Genetics 25 min
- The Nanney/Felts Family: Late-Onset Alzheimer's Genetics 20 min
- The Quest for Biomarkers 17 min
Video: Inside the Brain: Unraveling the Mystery of Alzheimer's Disease
This 4-minute captioned video shows the progression of Alzheimer's disease in the brain.
Inside the Brain: An Interactive Tour
The Brain Tour explains how the brain works and how Alzheimer's affects it.
Alzheimer's Disease: Unraveling the Mystery
This book explains what AD is, describes the main areas in which researchers are working, and highlights new approaches for helping families and friends care for people with AD.
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- Rapid advances in our knowledge about AD have led to the development of promising new drugs and treatment strategies. However, before these new strategies can be used in clinical practice, they must be shown to work in people. Advances in prevention and treatment are only possible thanks to volunteers who participate in clinical trials.
- Among those touched by Alzheimer's (excluding self), nearly one-third provide support as a friend or relative, another 3% provide support as a healthcare professional, and the remaining two-thirds provide no support to the person suffering from Alzheimer's. When support is provided, it most often entails emotional support, followed by care-giving support. While small in comparison, more than one person in ten is providing financial support. Read more.